658 research outputs found

    ISOTOPIC ANALYSIS OF JURASSIC (CALLOVIAN) MOLLUSKS FROM THE CHRISTIAN MALFORD LAGERSTATTE (UK): IMPLICATIONS FOR OCEAN WATER TEMPERATURE ESTIMATES BASED ON BELEMNOIDS

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    Isotopic data (C and O) derived from Callovian (Middle Jurassic) mollusks (bivalves, ammonites and belemnoids, including true belemnites and Belemnotheutis) are presented from a narrow stratigraphic interval in the Christian Malford Lagerstätte, UK. The exceptionally well-preserved mollusks include aragonite-calcite pairs precipitated by individual belemnite animals that enable an assessment of possible “vital” effects and the reliability of using belemnite calcite to determine ocean water compositions. The oxygen isotope data derived from the calcitic rostra of the belemnites (Cylindroteuthis) show modest variability, ranging from −1.2 to 0.9‰ (V-PDB), while their accompanying aragonitic phragmocones range from −1.4 to 0.0‰. Data derived from the ammonite Kosmoceras show some scatter, with oxygen isotope values varying from −3.6 to −0.2‰. The aragonite data from Cylindroteuthis, Kosmoceras and Belemnotheutis all overlap, suggesting they inhabited similar (surface) water depths. However, the corresponding data from the calcitic rostra of the Cylindroteuthis specimens suggest temperatures ∼ 5°C cooler. As we have analyzed aragonite-calcite pairs, the discrepancy cannot be explained by environmental effects. Though clearly a vital effect, it is difficult to resolve whether the temperatures derived from the aragonite (phragmocone) are too warm or from the calcite (rostrum) are too cool. Consequently, the applicability of standard paleotemperature equations to Cylindroteuthid belemnite rostra remains unproven. Sequentially sampled ontogenetic isotope data derived from Belemnotheutis phragmocones reveal only modest δ18O variation, consistent with limited movement between warmer (shallower) and cooler (deeper) waters. A coincidental systematic pattern of δ13C enrichment may signal changes in metabolic activity associated with a shift in ecology or feeding with age

    The history of the Y chromosome in man

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    Studies of the Y chromosome over the past few decades have opened a window into the history of our species, through the reconstruction and exploitation of a patrilineal (Y-genealogical) tree based on several hundred single-nucleotide variants (SNVs). A new study validates, refines and extends this tree by incorporating >65,000 Y-linked variants identified in 1,244 men representing worldwide diversity

    Reconstructing the Christian Malford ecosystem in the Oxford Clay Formation (Callovian, Jurassic) of Wiltshire: exceptional preservation, taphonomy, burial and compaction

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    &lt;p&gt;&lt;strong&gt;Abstract.&lt;/strong&gt; The Christian Malford lagerstätte in the Oxford Clay Formation of Wiltshire contains exceptionally well-preserved squid-like cephalopods, including &lt;i&gt;Belemnotheutis antiquus&lt;/i&gt; (Pearce). Some of these fossils preserve muscle tissue, contents of ink sacks and other soft parts of the squid, including arms with hooks in situ and the head area with statoliths (ear bones) present in life position. The preservation of soft-tissue material is usually taken as an indication of anoxic or dysaerobic conditions on the sea floor and within the enclosing sediments. Interestingly, in the prepared residues of all these sediments there are both statoliths and arm hooks as well as abundant, species-rich, assemblages of both foraminifera and ostracods. Such occurrences appear to be incompatible with an interpretation of potential sea floor anoxia.&lt;/p&gt; &lt;p&gt;The mudstones of the Oxford Clay Formation may have been compacted by 70&amp;amp;thinsp;%–80&amp;amp;thinsp;% during de-watering and burial, and in such a fine-grained lithology samples collected for microfossil examination probably represent several thousand years and, therefore, a significant number of foraminiferal life cycles. Such samples (even if only 1–2&amp;amp;thinsp;cm thick) could, potentially, include several oxic–anoxic cycles and, if coupled with compaction, generate the apparent coincidence of well-preserved, soft-bodied, cephalopods and diverse assemblages of benthic foraminifera.&lt;/p&gt; </jats:p

    Characterization of hunter-gatherer networks and implications for cumulative culture

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    Social networks in modern societies are highly structured, usually involving frequent contact with a small number of unrelated friends' 1. However, contact network structures in traditional small-scale societies, especially hunter-gatherers, are poorly characterized. We developed a portable wireless sensing technology (motes) to study within-camp proximity networks among Agta and BaYaka hunter-gatherers in fine detail. We show that hunter-gatherer social networks exhibit signs of increased efficiency 2 for potential information exchange. Increased network efficiency is achieved through investment in a few strong links among non-kin friends' connecting unrelated families. We show that interactions with non-kin appear in childhood, creating opportunities for collaboration and cultural exchange beyond family at early ages. We also show that strong friendships are more important than family ties in predicting levels of shared knowledge among individuals. We hypothesize that efficient transmission of cumulative culture 3-6 may have shaped human social networks and contributed to our tendency to extend networks beyond kin and form strong non-kin ties

    Applicability of an abbreviated version of the Child-OIDP inventory among primary schoolchildren in Tanzania

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    Background: There is a need for studies evaluating oral health related quality of life (OHRQoL) of children in developing countries. Aim: to assess the psychometric properties, prevalence and perceived causes of the child version of oral impact on daily performance inventory (Child- OIDP) among school children in two socio-demographically different districts of Tanzania. Socio-behavioral and clinical correlates of children's OHRQoL were also investigated.Method: One thousand six hundred and one children ( mean age 13 yr, 60.5% girls) attending 16 ( urban and rural) primary schools in Kinondoni and Temeke districts completed a survey instrument in face to face interviews and participated in a full mouth clinical examination. The survey instrument was designed to measure a Kiswahili translated and culturally adapted Child-OIDP frequency score, global oral health indicators and socio-demographic factors. Results: The Kiswahili version of the Child- OIDP inventory preserved the overall concept of the original English version and revealed good reliability in terms of Cronbach's alpha coefficient of 0.77 ( Kinondoni: 0.62, Temeke: 0.76). Weighted Kappa scores from a test-retest were 1.0 and 0.8 in Kinondoni and Temeke, respectively. Validity was supported in that the OIDP scores varied systematically and in the expected direction with self-reported oral health measures and socio-behavioral indicators. Confirmatory factor analyses, CFA, confirmed three dimensions identified initially by Principle Component Analysis within the OIDP item pool. A total of 28.6% of the participants had at least one oral impact. The area specific rates for Kinondoni and Temeke were 18.5% and 45.5%. The most frequently reported impacts were problems eating and cleaning teeth, and the most frequently reported cause of impacts were toothache, ulcer in mouth and position of teeth. Conclusion: This study showed that the Kiswahili version of the Child- OIDP was applicable for use among schoolchildren in Tanzania

    Aidnogenesis via Leptogenesis and Dark Sphalerons

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    We discuss aidnogenesis, the generation of a dark matter asymmetry via new sphaleron processes associated to an extra non-abelian gauge symmetry common to both the visible and the dark sectors. Such a theory can naturally produce an abundance of asymmetric dark matter which is of the same size as the lepton and baryon asymmetries, as suggested by the similar sizes of the observed baryonic and dark matter energy content, and provide a definite prediction for the mass of the dark matter particle. We discuss in detail a minimal realization in which the Standard Model is only extended by dark matter fermions which form "dark baryons" through an SU(3) interaction, and a (broken) horizontal symmetry that induces the new sphalerons. The dark matter mass is predicted to be approximately 6 GeV, close to the region favored by DAMA and CoGeNT. Furthermore, a remnant of the horizontal symmetry should be broken at a lower scale and can also explain the Tevatron dimuon anomaly.Comment: Minor changes, discussion of present constraints expanded. 16 pages, 2 eps figures, REVTeX

    Linkage mapping bovine EST-based SNP

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    BACKGROUND: Existing linkage maps of the bovine genome primarily contain anonymous microsatellite markers. These maps have proved valuable for mapping quantitative trait loci (QTL) to broad regions of the genome, but more closely spaced markers are needed to fine-map QTL, and markers associated with genes and annotated sequence are needed to identify genes and sequence variation that may explain QTL. RESULTS: Bovine expressed sequence tag (EST) and bacterial artificial chromosome (BAC)sequence data were used to develop 918 single nucleotide polymorphism (SNP) markers to map genes on the bovine linkage map. DNA of sires from the MARC reference population was used to detect SNPs, and progeny and mates of heterozygous sires were genotyped. Chromosome assignments for 861 SNPs were determined by twopoint analysis, and positions for 735 SNPs were established by multipoint analyses. Linkage maps of bovine autosomes with these SNPs represent 4585 markers in 2475 positions spanning 3058 cM . Markers include 3612 microsatellites, 913 SNPs and 60 other markers. Mean separation between marker positions is 1.2 cM. New SNP markers appear in 511 positions, with mean separation of 4.7 cM. Multi-allelic markers, mostly microsatellites, had a mean (maximum) of 216 (366) informative meioses, and a mean 3-lod confidence interval of 3.6 cM Bi-allelic markers, including SNP and other marker types, had a mean (maximum) of 55 (191) informative meioses, and were placed within a mean 8.5 cM 3-lod confidence interval. Homologous human sequences were identified for 1159 markers, including 582 newly developed and mapped SNP. CONCLUSION: Addition of these EST- and BAC-based SNPs to the bovine linkage map not only increases marker density, but provides connections to gene-rich physical maps, including annotated human sequence. The map provides a resource for fine-mapping quantitative trait loci and identification of positional candidate genes, and can be integrated with other data to guide and refine assembly of bovine genome sequence. Even after the bovine genome is completely sequenced, the map will continue to be a useful tool to link observable phenotypes and animal genotypes to underlying genes and molecular mechanisms influencing economically important beef and dairy traits

    Molecular, serological and biological variation among chickpea chlorotic stunt virus isolates from five countries of North Africa and West Asia

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    Chickpea chlorotic stunt virus (CpCSV), a proposed new member of the genus Polerovirus (family Luteoviridae), has been reported only from Ethiopia. In attempts to determine the geographical distribution and variability of CpCSV, a pair of degenerate primers derived from conserved domains of the luteovirus coat protein (CP) gene was used for RT-PCR analysis of various legume samples originating from five countries and containing unidentified luteoviruses. Sequencing of the amplicons provided evidence for the occurrence of CpCSV also in Egypt, Morocco, Sudan, and Syria. Phylogenetic analysis of the CP nucleotide sequences of 18 samples from the five countries revealed the existence of two geographic groups of CpCSV isolates differing in CP sequences by 8–10%. Group I included isolates from Ethiopia and Sudan, while group II comprised those from Egypt, Morocco and Syria. For distinguishing these two groups, a simple RFLP test using HindIII and/or PvuII for cleavage of CP-gene-derived PCR products was developed. In ELISA and immunoelectron microscopy, however, isolates from these two groups could not be distinguished with rabbit antisera raised against a group-I isolate from Ethiopia (CpCSV-Eth) and a group-II isolate from Syria (CpCSV-Sy). Since none of the ten monoclonal antibodies (MAbs) that had been produced earlier against CpCSV-Eth reacted with group-II isolates, further MAbs were produced. Of the seven MAbs raised against CpCSV-Sy, two reacted only with CpCSV-Sy and two others with both CpCSV-Sy and -Eth. This indicated that there are group I- and II-specific and common (species-specific) epitopes on the CpCSV CP and that the corresponding MAbs are suitable for specific detection and discrimination of CpCSV isolates. Moreover, CpCSV-Sy (group II) caused more severe stunting and yellowing in faba bean than CpCSV-Eth (group I). In conclusion, our data indicate the existence of a geographically associated variation in the molecular, serological and presumably biological properties of CpCSV
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